1. Field of the Invention
The present invention relates generally to the maintenance of seawalls disposed between bodies of water and retained earth and, more particularly, to methods, systems and apparatus for maintaining seawalls using anchoring devices to strengthen the seawalls to resist potential damage and/or repair actual damage in the seawalls.
2. Discussion of the Related Art
Seawalls are commonly installed between bodies of water and earth to provide physical boundaries between the bodies of water and the earth and to support or retain the earth by resisting the pressure of the retained earth against the seawalls. Seawalls can be used to separate earth from various types of bodies of water of various sizes and depths. Seawalls can be constructed in various ways and of various materials. Typically, seawalls have a vertical span or height sufficient for an upper end of the seawall to normally extend above the water with a lower end or toe portion of the seawall embedded in the earthen floor to extend below the body of water. The distance that a seawall extends above the water may vary depending on the height of the retained earth above the water and/or anticipated fluctuations in water level. The depth to which the embedded toe portion extends below the water into the earthen floor may vary in accordance with the vertical span of the seawall, the height of the retained earth and/or the depth of the body of water to provide sufficient support for the seawall to resist movement from the pressure of the retained earth against the seawall. Accordingly, seawalls are usually designed for a particular depth body of water. The thickness of seawalls may vary depending on site-specific loads and other engineering parameters. One representative type of seawall comprises concrete panels about ten to fifteen feet high, about four feet wide and about four to ten inches thick disposed in side by side abutment to form a continuous wall. Oftentimes vertical pilings are installed in the water close to the water facing side of a seawall at spaced locations along the seawall, with lower ends of the pilings being driven into the earthen floor and upper ends of the pilings typically extending above the water. The pilings are sometimes installed as part of the original seawall installation.
Since the retained earth exerts greater pressure against seawalls than the pressure exerted against the seawalls by the water, seawalls are oftentimes damaged or destabilized during their lifetimes as evidenced, for example, by movement, displacement, shifting, cracking and/or misalignment of the seawalls. Sometimes seawalls are placed at risk for damage or instability due to a change in conditions occurring subsequent to installation of the seawalls. For instance, a body of water may be dredged and/or erosion of the earthen floor may occur subsequent to installation of a seawall, resulting in a greater depth body of water and a lesser depth of penetration for the toe portion of the seawall into the earthen floor. The lesser depth of penetration for the toe portion into the earthen floor may no longer be sufficient for the seawall to support the pressure of the retained earth such that the seawall is susceptible to damage or instability. In some cases, the height of the retained earth on the earth facing side of an existing seawall may be increased, causing increased pressure of retained earth against the seawall by which the seawall may be damaged or destabilized. A type of damage known as “toe out” may occur in seawalls where the toe portion shifts or displaces outwardly in a direction away from the retained earth due to the toe portion being insufficiently embedded in the earthen floor. In addition to the pressures of retained earth, seawalls may be damaged or destabilized directly or indirectly due to other conditions including collisions or other impacts, corrosion, environmental factors, and age. Since removal and replacement of damaged and/or unstable seawalls involves significant cost and disruption, it is preferable to strengthen existing seawalls to repair and/or avoid damage or instability.
One traditional method for arresting movement of seawalls involves installing vertical pilings in the water close to the water facing side of a seawall by driving lower ends of the pilings into the earthen floor. Depending on how close the pilings are to the seawall, cement bags may be packed between the pilings and the seawall to resist seawall movement. Sometimes vertical pilings are installed to shore up an undamaged portion of a seawall while repairs are made to another portion of the seawall that is in total failure. Another traditional method for arresting movement of seawalls entails the placement of riprap on the earthen floor adjacent the water facing side of a seawall. The latter methods are costly, obtrusive, and can initiate damage in other portions of the seawall. Where vertical pilings are used to shore up a portion of a seawall, installation of the pilings can cause portions of the seawall farther down to fail in a “domino” effect.
It has been proposed to strengthen seawalls to resist movement using anchors or tie rods in conjunction with cementitious material as represented by U.S. Pat. No. 1,270,659 to Ravier, U.S. Pat. No. 4,480,945 to Schnabel, Jr., U.S. Pat. No. 4,711,604 to Heimsoth et al., and U.S. Pat. No. 4,728,225 to Brandl et al. Heimsoth et al also discloses an installation system for drilling a passage through the seawall and installing the anchor through the passage from the water facing side of the seawall. However, the installation system of Heimsoth et al requires heavy equipment necessitating major cost and effort to transport and assemble, and requires that heavy equipment be placed on land on the earth facing side of the seawall. U.S. Pat. No. 3,371,494 to Lagerstrom, U.S. Pat. No. 4,253,781 to Fischer et al., and U.S. Pat. No. 4,911,582 to Pierce, Jr. et al. disclose the use of anchors or tie rods in conjunction with cementitious material to restrain structural walls other than seawalls. Helical anchors for building constructions are represented by U.S. Pat. No. 4,499,698 to Hoyt et al., U.S. Pat. No. 5,011,366 to Hamilton, et al., U.S. Pat. No. 5,120,163 to Holdeman et al., U.S. Pat. No. 5,139,368 and No. 5,171,107 to Hamilton et al., U.S. Pat. No. 5,213,448 to Seider et al., and U.S. Pat. No. 5,927,905 to van Halteren. U.S. Pat. No. 3,999,398 to Kurose discloses the use of anchor bolts in the installation of new retaining walls, but does not pertain to the stabilization of existing retaining walls or seawalls.
Prior apparatus and methods for repairing and/or strengthening seawalls and other retaining walls have various disadvantages including complicated structure and installation steps, major disruption, the need for excavating and/or disturbing the earth, the need to bring heavy machinery onto property on the earth facing side of the seawall, lengthy regulatory permitting requirements, partial or complete demolition of existing walls, the need to temporarily hold back or contain water during installation, the need to install additional and/or replacement wall structure, substantial duration of time from start to completion of work, the use of cementitious material to assist in anchoring, the need for backfill, and the inability to execute seawall stabilization from the water side of the seawall. Prior apparatus and methods which require substantial earth-side access or earth-side excavation are untenable where homes, other structures such as docks and pools, and/or landscaping are situated close to seawalls, making it undesirable and even prohibitive to disturb the earth or bring heavy equipment onto the land on the earth facing side of the seawall and/or to conduct seawall maintenance from the earth facing side. Prior attempts at stabilizing seawalls have failed to provide an integrated system of components to accomplish stabilization of various types of seawalls quickly, efficiently and economically from the water side of the seawall. Prior apparatus for repairing and/or strengthening seawalls and other retaining walls are essentially static and non-adjustable, and the use of cementitious material generally prevents adjustability in response to dynamic changes in the walls. Prior apparatus for repairing and/or strengthening seawalls and other retaining walls are essentially permanent and non-removable, especially where cementitious material is utilized. Prior apparatus for repairing seawalls and other retaining walls are in general unsuitable for monitoring changes occurring in the walls over time. Many prior apparatus and methods for repairing seawalls are environmentally incompatible and result in significant obstruction of or intrusion into the body of water on the water facing side of the seawall. Prior apparatus and methods for repairing and/or strengthening seawalls and other retaining walls using anchors or tie rods generally lack the ability to rigidly interconnect a plurality of spaced anchors or tie rods installed in a wall to maintain the spacing between the anchors or tie rods in a desired direction. Furthermore, prior apparatus and methods for repairing and/or maintaining seawalls and other retaining walls using anchors or tie rods do not allow a plurality of spaced anchors or tie rods installed in a wall to be adjustably interconnected to adjust the spacing between the anchors or tie rods. Prior apparatus and methods for repairing and/or strengthening seawalls and other retaining walls do not contemplate closing openings in the walls by adjustably moving the walls between interconnected anchors or tie rods installed in the walls on opposite sides of the openings.